The shimmering gown, which is split to the knee and has accentuated shoulder pads, was commissioned for her in 1986 by Walker, who was her much loved go-to designer.

She wore it on a State visit to Austria the same year and many times after.

Auctioneer Kerry Taylor said: "It is unusually glitzy being entirely covered in shimmering sequins - more Hollywood glam than the sedate, elegant numbers she usually wore."

She added: "It was obviously something of a favourite as she wore it many times."

The Duchess of Cambridge has followed in Diana's footsteps by wearing Catherine Walker, last opting for the label when she chose a grass-green coat dress for her appearance at the Chelsea Flower Show last week.

The second outfit - a bold tartan-check wool coat with wide, padded shoulders, the princess's trademark sailor-collar and a matching skirt - was not a popular look.

It was likened to a horse blanket by the media after Diana wore it on a trip to Venice with the Prince of Wales in 1985.

Made by Elizabeth and David Emanuel, who designed Diana's wedding dress, it ended up in a resale clothes shop after being handed over by the mother of Duchess of York Sarah Ferguson.

Diana was also photographed wearing the coat while holding baby Prince Harry on board the Royal Yacht Britannia on the same trip to Italy.

Taylor said: "The Press at the time - always so keen to comment on everything Diana did and wore - unflatteringly likened the outfit to a horse blanket, which is maybe why it ended up in a high-end clothes resale shop in Hampshire some years later.

"The vendor purchased the ensemble from there in 1990 and was told by the shop keeper at the time that the clothes had come to her via Susan Barrantes, mother of Sarah Ferguson."

The outfit is expected to fetch between £10,000 and £15,000 when it goes under the hammer.

Kerry Taylor Auctions' Passion for Fashion sale will be held on June 14 in Bermondsey, south east London.